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A cooling system is provided which includes, for instance, a coolant
supply manifold, a multifunction coolant manifold structure, and multiple
cooling structures. The multifunction coolant manifold structure includes
a coolant-commoning manifold and an auxiliary coolant reservoir above and
in fluid communication with the coolant-commoning manifold. The multiple
cooling structures are coupled in parallel fluid communication between
the coolant supply and coolant-commoning manifolds to receive coolant
from the supply, and exhaust coolant to the coolant-commoning manifold.
The coolant-commoning manifold is sized to slow therein a flow rate of
coolant exhausting from the multiple cooling structures to allow gas
within the exhausting coolant to escape the coolant within the
coolant-commoning manifold. The escaping gas rises to the auxiliary
coolant reservoir and is replaced within the coolant-commoning manifold
by coolant from the auxiliary coolant reservoir.

1. A method comprising: providing a cooling system, the providing of the
cooling system including: providing a coolant loop comprising a coolant;
providing a heat exchange assembly coupled to the coolant loop to cool
coolant within the coolant loop; providing a coolant supply manifold
coupled to the coolant loop; providing a multifunction coolant manifold
structure to deaerate the coolant, the multifunction coolant supply
manifold structure being coupled to the coolant loop and being separate
from the heat exchange assembly, the multifunction coolant supply
manifold structure including: a coolant-commoning manifold; an auxiliary
coolant reservoir disposed above and in fluid communication with the
coolant-commoning manifold; and providing multiple cooling structures
coupled to the coolant loop in parallel fluid communication between the
coolant supply manifold and the coolant-commoning manifold to receive
coolant from the coolant supply manifold, and exhaust coolant to the
coolant-commoning manifold; the multifunction coolant manifold structure
comprising both the coolant-commoning manifold and a coolant distribution
manifold portion integrated together in a single structure, and wherein
the multifunction coolant manifold structure is sized larger than the
coolant supply manifold; and wherein the multifunction coolant manifold
structure deaerates the coolant by the coolant-commoning manifold being
sized larger than the coolant supply manifold to slow therein a flow rate
of coolant exhausting from the multiple cooling structures as the coolant
enters the coolant-commoning manifold to allow gas within the exhausting
coolant to escape the coolant within the coolant-commoning manifold, the
escaping gas within the coolant-commoning manifold rising to the
auxiliary coolant reservoir, and being replaced within the
coolant-commoning manifold by coolant from the auxiliary coolant
reservoir.

2. The method of claim 1, wherein the multifunction coolant manifold
structure is a single, integrated and rigid structure, and wherein the
coolant-commoning manifold has a larger dimension in a first direction
compared with that of the auxiliary coolant reservoir, and the auxiliary
coolant reservoir has a larger dimension in a second direction compared
with that of the coolant-commoning manifold.

3. The method of claim 2, wherein the first direction is a vertical
direction, and the second direction is a horizontal direction.

4. The method of claim 1, wherein the auxiliary coolant reservoir is
coupled in fluid communication with the coolant-commoning manifold via a
detachable coolant conduit.

5. The method of claim 4, wherein the multifunction coolant manifold
structure comprises a field-replaceable unit, the field-replaceable unit
comprising the auxiliary coolant reservoir, and including one or more
components for at least one of monitoring or controlling one or more
characteristics of the coolant within the multifunction coolant manifold
structure.

6. The method of claim 5, wherein the multifunction coolant manifold
structure is configured for the field-replaceable unit to be replaceable
while the cooling system is operational, with coolant exhausting from the
multiple cooling structures to the coolant-commoning manifold of the
multifunction coolant manifold structure.

7. The method of claim 1, wherein the coolant pumping assembly comprises
at least two modular pumping units coupled in parallel fluid
communication to the multifunction coolant manifold structure for pumping
coolant in parallel from the multifunction coolant manifold structure.

8. The method of claim 1, further comprising providing a coolant fill
port within the auxiliary coolant reservoir, below a top of the auxiliary
coolant reservoir to assist in defining a gas pocket in an upper portion
thereof as a coolant expansion region.

9. The method of claim 1, wherein the auxiliary coolant reservoir further
comprises a vacuum breaker to prevent cavitation within the cooling
system, and a pressure-relief valve to prevent the cooling system from
over-pressurizing.

10. The method of claim 1, further comprising providing one or more
coolant level sensors associated with the auxiliary coolant reservoir to
sense level of coolant within the multifunction coolant manifold
structure.

Description

BACKGROUND

[0001] The power dissipation of integrated circuit chips, and the modules
containing the chips, continues to increase in order to achieve increases
in processor performance. This trend poses cooling challenges at the
module, system, rack and data center levels.

[0002] In many large server applications, processors along with their
associated electronics (e.g., memory, disk drives, power supplies, etc.)
are packaged in removable drawer configurations stacked within an
electronics rack or frame comprising information technology (IT)
equipment. In other cases, the electronics may be in fixed locations
within the rack or frame. Conventionally, the components have been cooled
by air moving in parallel airflow paths, usually front-to-back, impelled
by one or more air moving assemblies (e.g., axial or centrifugal fans).
In some cases it has been possible to handle increased power dissipation
within a single drawer or system by providing greater airflow, for
example, through the use of more powerful air moving assemblies or by
increasing the rotational speed (i.e., RPMs) of the fan mechanisms.
However, this approach is becoming problematic, particularly in the
context of a computer center installation (i.e., data center).

[0003] The sensible heat load carried by the air exiting the rack(s) is
stressing the capability of the room air-conditioning to effectively
handle the load. This is especially true for large installations with
"server farms" or large banks of computer racks located close together.
In such installations, liquid-cooling is an attractive technology to
selectively manage the higher heat fluxes. The liquid absorbs the heat
dissipated by the components/modules in an efficient manner. Typically,
the heat is ultimately transferred from the liquid coolant to a heat
sink, whether air or other liquid-based.

SUMMARY

[0004] The shortcomings of the prior art are addressed and additional
advantages are provided through the provision, in one aspect, of a method
which includes providing a cooling system. Providing the cooling system
includes providing a coolant loop including a coolant, and providing a
heat exchange assembly coupled to the coolant loop to cool coolant within
the coolant loop. Further, providing the cooling system includes
providing a coolant supply manifold coupled to the coolant loop, and
providing a multifunction coolant manifold structure to deaerate the
coolant. The multifunction coolant manifold structure is coupled to the
coolant loop and is separate from the heat exchange assembly. The
multifunction coolant manifold structure includes a coolant-commoning
manifold, and an auxiliary coolant reservoir disposed above and in fluid
communication with the coolant-commoning manifold. Further, providing the
cooling system includes providing multiple cooling structures coupled to
the coolant loop in parallel fluid communication between the coolant
supply manifold and the coolant-commoning manifold to receive coolant
from the coolant supply manifold, and exhaust coolant to the
coolant-commoning manifold. The multifunction coolant manifold structure
includes both the coolant-commoning manifold and a coolant distribution
manifold portion integrated together in a single structure, where the
multifunction coolant manifold structure is sized larger than the coolant
supply manifold. The multifunction coolant manifold structure deaerates
the coolant by the coolant-commoning manifold being sized larger than the
coolant supply manifold to slow therein a flow rate of coolant exhausting
from the multiple cooling structures as the coolant enters the
coolant-commoning manifold to allow gas within the exhausting coolant to
escape the coolant within the coolant-commoning manifold. The escaping
gas within the coolant-commoning manifold rises to the auxiliary coolant
reservoir, and is replaced within the coolant-commoning manifold by
coolant from the auxiliary coolant reservoir.

[0005] Additional features and advantages are realized through the
techniques of the present invention. Other embodiments and aspects of the
invention are described in detail herein and are considered a part of the
claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] One or more aspects of the present invention are particularly
pointed out and distinctly claimed as examples in the claims at the
conclusion of the specification. The foregoing and other objects,
features, and advantages of the invention are apparent from the following
detailed description taken in conjunction with the accompanying drawings
in which:

[0007] FIG. 1 depicts one embodiment of a raised floor layout of an
air-cooled data center, which may employ one or more cooling systems, in
accordance with one or more aspects of the present invention;

[0008] FIG. 2 is a cross-sectional elevational view of one implementation
of an electronics rack for a data center, which may employ a cooling
system, in accordance with one or more aspects of the present invention;

[0009] FIG. 3A is a schematic of one embodiment of a cooled electronics
assembly having multiple electronic systems and a cooling system, in
accordance with one or more aspects of the present invention;

[0010] FIG. 3B is a plan view of one embodiment of an electronic system
layout illustrating, by way of example, a hybrid cooling approach for
cooling components of the electronic system using, in part, a cooling
system, in accordance with one or more aspects of the present invention;

[0011] FIG. 4 is a schematic of another embodiment of a cooled electronics
assembly having multiple electronic systems and a cooling system, in
accordance with one or more aspects of the present invention;

[0012] FIG. 5A depicts one detailed embodiment of a partially-assembled,
cooled electronic assembly comprising multiple electronic systems and a
cooling system, in accordance with one or more aspects of the present
invention;

[0013] FIG. 5B is an enlarged depiction of one embodiment of the
multifunction coolant manifold structure of the cooling system of FIG.
5A, in accordance with one or more aspects of the present invention;

[0014] FIG. 6A depicts another embodiment of a partially-assembled, cooled
electronic assembly comprising multiple electronic systems and a cooling
system, in accordance with one or more aspects of the present invention;
and

[0015] FIG. 6B is an enlarged depiction of one embodiment of the
multifunction coolant manifold structure of the cooling system of FIG.
6A, in accordance with one or more aspects of the present invention.

DETAILED DESCRIPTION

[0016] As used herein, the terms "electronics rack" and "rack unit" are
used interchangeably, and unless otherwise specified include any housing,
frame, rack, compartment, blade server system, etc., having one or more
heat-generating components of a computer system, electronic system,
information technology (IT) equipment, etc., and may include, for
example, a stand-alone computer processor having high-, mid- or low-end
processing capability. In one embodiment, an electronics rack may
comprise a portion of an electronic system, a single electronic system,
or multiple electronic systems, for example, in one or more subsystems,
sub-housings, blades, drawers, nodes, compartments, boards, etc., having
one or more heat-generating electronic components disposed therein or
thereon. An electronic system may be movable or fixed, for example,
relative to an electronics rack, with rack-mounted electronic drawers of
a rack unit and blades of a blade center system being two examples of
electronic systems of an electronics rack to be cooled. In one
embodiment, an electronic system may comprise multiple electronic
components, and may be, in one example, a server unit.

[0017] "Electronic component" refers to any heat generating electronic
component of, for example, an electronic system requiring cooling. By way
of example, an electronic component may comprise one or more integrated
circuit die and/or other electronic devices to be cooled, including one
or more processor die, memory die or memory support die. As a further
example, an electronic component may comprise one or more bare die or one
or more packaged die disposed on a common carrier. Further, unless
otherwise specified herein, the term "coolant-cooled cold plate" refers
to any conventional thermally conductive, heat transfer structure having
a plurality of channels or passageways formed therein for flowing of
coolant, such as liquid coolant, therethrough.

[0018] As used herein, "coolant-to-air heat exchanger" means any heat
exchange mechanism characterized as described herein, across which air
passes and through which coolant, such as liquid coolant, can circulate;
and includes, one or more discrete heat exchangers, coupled either in
series or in parallel. A coolant-to-air heat exchanger may comprise, for
example, one or more coolant flow paths, formed of thermally conductive
tubing (such as copper or other tubing) thermally coupled to a plurality
of fins across which air passes. Size, configuration and construction of
the coolant-to-air heat exchanger can vary without departing from the
scope of the invention disclosed herein. Further, "data center" refers to
a computer installation containing one or more electronics racks to be
cooled. As a specific example, a data center may include one or more rows
of rack-mounted computing units, such as server units.

[0019] One example of the coolant is water. However, the concepts
disclosed herein are readily adapted to use with other types of coolant.
For example, the coolant may comprise a brine, a dielectric liquid, a
fluorocarbon liquid, a liquid metal, or other coolant, or refrigerant,
while still maintaining the advantages and unique features of the present
invention.

[0020] Reference is made below to the drawings, wherein the same or
similar reference numbers used throughout different figures designate the
same or similar components.

[0021] As shown in FIG. 1, in one implementation of a raised floor layout
of an air-cooled data center 100, multiple electronics racks 110 are
disposed in one or more rows. A computer installation such as depicted in
FIG. 1 may house several hundred, or even several thousand
microprocessors. In the arrangement of FIG. 1, chilled air enters the
computer room via floor vents from a supply air plenum 145 defined
between a raised floor 140 and a base or sub-floor 165 of the room.
Cooled air is taken in through louvered covers at air inlet sides 121 of
the electronics racks and expelled through the back (i.e., air outlet
sides 131) of the electronics racks. Electronics racks 110 may have one
or more air-moving devices (e.g., axial or centrifugal fans) to provide
forced inlet-to-outlet air flow to cool the electronic components within
the rack units. The supply air plenum 145 provides (in one embodiment)
conditioned and cooled air to the air-inlet sides of the electronics
racks via perforated floor tiles 160 disposed in a "cold" aisle of the
computer installation. The cooled air is supplied to plenum 145 by one or
more air conditioning units 150, also disposed within data center 100.
Room air is taken into each air conditioning unit 150 near an upper
portion thereof. This room air may comprise (in part) exhausted air from
the "hot" aisles of the computer installation defined by opposing air
outlet sides 131 of the electronics racks 110.

[0022] FIG. 2 depicts (by way of example) one embodiment of an electronics
rack 110 with a plurality of electronic systems 201 to be cooled. In the
embodiment illustrated, electronic systems 201 are air-cooled by cool
airflow 202 ingressing via air inlet side 121, and exhausting out air
outlet side 131 as heated airflow 203. By way of example, one or more
air-moving assemblies 208 may be provided at the air inlet sides of
electronic systems 201 and/or one or more air-moving assemblies 209 may
be provided at the air outlet sides of electronic systems 201 to
facilitate airflow through the individual systems 201 as part of the
cooling apparatus of electronics rack 110. For instance, air-moving
assemblies 208 at the air inlets to electronic systems 201 may be or
include axial fan assemblies, while air-moving assemblies 209 disposed at
the air outlets of electronic systems 201 may be or include centrifugal
fan assemblies. One or more electronic systems 201 may include
heat-generating components to be cooled of, for instance, an electronic
subsystem, and/or information technology (IT) equipment. More
particularly, one or more of the electronic systems 201 may include one
or more processors and associated memory.

[0023] In one embodiment, electronics rack 110 may also include, by way of
example, one or more bulk power assemblies 204 of an AC to DC power
supply assembly. AC to DC power supply assembly further includes, in one
embodiment, a frame controller, which may be resident in the bulk power
assembly 204 and/or in one or more electronic systems 201. Also
illustrated in FIG. 2 is one or more input/output (I/O) drawer(s) 205,
which may also include a switch network. I/O drawer(s) 205 may include,
as one example, PCI slots and disk drivers for the electronics rack.

[0024] In the depicted implementation, a three-phase AC source feeds power
via an AC power supply line cord 206 to bulk power assembly 204, which
transforms the supplied AC power to an appropriate DC power level for
output via distribution cable 207 to the plurality of electronic systems
201 and I/O drawer(s) 205. The number of electronic systems installed in
the electronics rack is variable, and depends on customer requirements
for a particular system. Note that the particular electronics rack 110
configuration of FIG. 2 is presented by way of example only, and not by
way of limitation. In particular, FIGS. 3A-6B depict, in part, other
alternate implementations of an electronics rack and cooling approaches.

[0025] Referring first to FIG. 3A, a schematic diagram is presented of one
embodiment of a cooled electronic assembly configured as a cooled
electronics rack 110', which includes multiple electronic systems 301 and
a cooling system, which may be disposed fully or partially internal to
the electronics rack, or in an alternate implementation, external, and
even remote from the electronics rack. In the depicted implementation,
electronic systems 301 each have an associated cooling structure (or heat
removal structure) of the cooling system. By way of example, one or more
of the cooling structures may comprise one or more coolant-cooled cold
plates, or one or more coolant-immersion housings depending, for
instance, whether indirect or direct liquid-assisted cooling is desired.
The cooling system further includes a coolant supply manifold 310 and a
coolant-commoning manifold 320, with the multiple cooling structures
being coupled in parallel fluid communication between coolant supply
manifold 310 and coolant-commoning manifold 320 to receive coolant from
the coolant supply manifold, and exhaust coolant to the coolant-commoning
manifold.

[0026] FIG. 3A depicts an example of a closed-loop cooling system, with
multiple control and monitor components that allow the system to operate
reliably. These components include one or more de-aerators 321 to remove
dissolved gasses from the coolant, a coolant expansion structure 322 to
accommodate expansion of coolant within the cooling system, a reservoir
323, one or more level sensors 324 associated with reservoir 323 to sense
level of coolant within the cooling system, a vacuum breaker 325 coupled
to the coolant loop of the cooling system to prevent cavitation of the
pumping assembly, and a pressure-relieve valve 326 associated with the
coolant loop to ensure that the cooling system does not over-pressurize.
A fill port 328 may be provided at the top of the cooling system, and a
drain port 329 may be provided in a lower portion of the cooling system.
As shown, reservoir 323 functions to supply coolant to a distribution
manifold 330 of a pumping assembly, which includes multiple pumping units
335, pump 1, pump 2, pump 3, each with an associated check valve 336.
Further, the pumping assembly includes a return manifold 340. As
illustrated, the pumping units 335 of the pumping assembly are coupled in
parallel fluid communication between distribution manifold 330 and return
manifold 340. In one implementation, the pumping units 335 are modular
pumping units (MPUs), which may be individually, selectively replaced
concurrent with continued operation of the cooling system of the cooled
electronic assembly depicted. Note that, in one implementation, the
components of the cooling system of FIG. 3A are discrete components which
fulfill the above-described functions.

[0027] As illustrated, the cooling system further includes a heat removal
section 350, coupled in fluid communication between return manifold 340
of the pump assembly and coolant supply manifold 310. By way of example,
heat removal section 350 includes one or more coolant-to-air heat
exchangers with one or more associated fan mechanisms (e.g., axial or
centrifugal fans) to facilitate air-cooling of coolant within the heat
exchanger(s) by flowing cooled air 300 across heat removal section 350.
After passing across heat removal section 350, the heated air egresses
from the rack unit as heated air 300'. Note that in an alternate
embodiment, the heat removal section could include one or more
coolant-to-coolant heat exchangers, or one or more liquid-to-liquid heat
exchangers, to reject heat from the coolant circulating through the
cooling system. For instance, the heat could be rejected to
facility-chilled water where available, rather than to cooled air 300.

[0028] In operation, heat generated within the electronic systems 301 is
extracted by coolant flowing through (for example) respective cooling
structures associated therewith, such as cold plates, and is returned via
the coolant-commoning manifold 320 and the active modular pumping unit(s)
(MPU) 335, for example, for rejection of the heat from the coolant to the
cooled ambient air 300 passing across the heat exchanger in heat removal
section 350. In one implementation, only one modular pumping unit 335 may
(depending on the mode) be active at a time, and the MPU redundancy
allows for, for example, servicing or replacement of an inactive modular
pumping unit from the cooling system, without requiring shut-off of the
electronic systems being cooled. By way of specific example, quick
connect couplings may be employed, along with appropriately sized and
configured hoses to couple, for example, the heat exchanger, cold plates,
supply and return manifolds, reservoir and pumping units. Redundant fan
mechanisms, such as redundant centrifugal fans, with appropriate,
redundant drive cards or controllers, may be mounted to direct cooled air
300 across the heat exchanger(s) of the heat removal section. These
controllers may be in communication with a system-level controller (not
shown), in one embodiment. In one normal mode implementation, the
multiple fan mechanisms may be running at the same time.

[0029] Auxiliary (or backup) air-cooling may be provided across the
electronic systems 301, for instance, in the case of a failure of the
coolant-based cooling apparatus which requires shut-off of coolant flow
to the electronic systems 301. In such a case, airflow may be drawn
through the rack from an air inlet side to an air outlet side thereof via
redundant backup fan mechanisms (not shown) and appropriate airflow
ducting. Note in this regard, that in one embodiment, the auxiliary
airflow cooling apparatus may be disposed above the multiple electronic
systems within the electronics rack, and the coolant-based cooling system
discussed herein may be disposed below the multiple electronic systems to
be cooled, as in the schematic of FIG. 3A.

[0030] Note that, although depicted with reference to FIG. 3A with respect
to one or more coolant-to-air heat exchangers, the cooling system(s)
disclosed herein may provide pumped coolant (such as water) for
circulation through various types of heat exchange assemblies, including
one or more coolant-to-air heat exchangers, one or more
coolant-to-coolant heat exchangers, a rack-mounted door heat exchanger, a
coolant-to-refrigerant heat exchanger, etc. Further, the heat exchange
assembly may comprise more than one heat exchanger, including more than
one type of heat exchanger, depending upon the implementation. The heat
exchange assembly, or more generally, heat removal section, could be
within the cooled electronics rack, or positioned remotely from the rack.

[0031] By way of example only, FIG. 3B depicts one embodiment of an
electronic system 301 component layout wherein one or more air moving
devices 208 provide forced air flow 300 to cool multiple components 304
within electronic system 301. Cool air is taken in through a front 302
and exhausted out a back 303 of the drawer. The multiple components to be
cooled include multiple processor modules to which cooling structures,
such as coolant-cooled cold plates 305 of the cooling system are coupled,
as well as multiple arrays of memory modules 306 (e.g., dual in-line
memory modules (DIMMs)) and multiple rows of memory support modules 307
(e.g., DIMM control modules) to which air-cooled heat sinks may be
coupled. In the embodiment illustrated, memory modules 306 and memory
support modules 307 are partially arrayed near front 302 of electronic
system 301, and partially arrayed near back 303 of electronic subsystem
301. Also, in the embodiment of FIG. 3B, memory modules 306 and the
memory support modules 307 are cooled by air flow 300 across the
electronic system.

[0032] The illustrated coolant-based cooling system further includes
multiple coolant-carrying tubes connected to and in fluid communication
with coolant-cooled cold plates 305. The coolant-carrying tubes comprise
sets of coolant-carrying tubes, with each set including (for example) a
coolant supply tube 315, a bridge tube 316 and a coolant return tube 317.
In this example, each set of tubes provides coolant to a series-connected
pair of cold plates 305 (coupled to a pair of processor modules). Coolant
flows into a first cold plate of each pair via the coolant supply tube
315 and from the first cold plate to a second cold plate of the pair via
bridge tube or line 316, which may or may not be thermally conductive.
From the second cold plate of the pair, coolant is returned through the
respective coolant return tube 317.

[0033] In FIGS. 3A & 3B, a closed-loop cooling system is illustrated which
incorporates a number of components that ensure that the cooling system
works reliably. These include, but are not necessarily limited to: a
coolant reservoir; coolant level sensors; a coolant expansion region; one
or more vacuum breakers; one or more pressure-relieve valves; a pumping
assembly which may include multiple modular pumping units; distribution
and return manifolds for pump flow through one or more parallel-coupled
pumping units of the pump assembly; check valves to prevent back flow
through one or more inactive pumps of the pump assembly; a separate
de-aerator facility to remove air or other gasses from the coolant within
the cooling system; a supply manifold to distribute coolant to multiple
cooling structures coupled in parallel; a coolant supply manifold; a
return manifold to receive exhaust coolant from the multiple cooling
structures; a heat removal section or mechanism, such as a coolant-to-air
heat exchanger; and fill and drain ports for filling and draining the
cooling system.

[0034] In one implementation, the above-noted components of the cooled
electronic assembly, and in particular, the noted components of the
cooling system, may be discrete components obtained, at least in part, as
commercially available components. However, implementing the cooling
system in this manner may add cost, space, and complexity to the cooling
system, as well as to the resultant cooled electronic assembly. In
accordance with aspects of the present invention, many of the above-noted
structures or functions may be integrated (or combined) within a single,
novel, multifunction coolant manifold structure.

[0035] For instance, in one embodiment, the multifunction coolant manifold
structure may include or provide: a coolant reservoir; one or more
coolant level sensors; a coolant expansion region; one or more vacuum
breakers to prevent pump cavitation; one or more pressure-relief valves
to ensure the cooling system does not over-pressurize; a distribution
manifold to distribute coolant to the pumping assembly; a de-aerator
facility to remove air and other gasses from the coolant within the
cooling system; a coolant-commoning manifold to common exhaust coolant
from multiple cooling structures; as well as one or more fill or drain
ports for the cooling system. Advantageously, combining components of the
cooling system into a single, multipurpose manifold structure saves cost,
reduces space, and reduces complexity of the cooling system, as well as
of the resultant cooled electronic assembly.

[0036] Generally stated, disclosed herein are cooling systems, cooled
electronic assemblies, and methods of fabrication, which include a
multifunction coolant manifold structure. For instance, the cooling
system may include a coolant supply manifold, a multifunction coolant
manifold structure, and multiple cooling structures. The multifunction
coolant manifold structure includes, in one embodiment, a
coolant-commoning manifold and an auxiliary coolant reservoir, which may
be disposed above and in fluid communication with the coolant-commoning
manifold. The multiple cooling structures are coupled in parallel fluid
communication between the coolant supply manifold and the
coolant-commoning manifold to receive coolant from the coolant supply
manifold, and exhaust coolant to the coolant-commoning manifold. The
coolant-commoning manifold is sized to slow a flow rate of coolant
exhausting from the multiple cooling structures to allow gas within the
exhausting coolant to escape the coolant within the coolant-commoning
manifold. The multifunction coolant manifold structure is configured for
the escaping gas (e.g., air bubbles) to rise to the auxiliary coolant
reservoir, and be replaced within the coolant-commoning manifold by
coolant from the auxiliary coolant reservoir.

[0037] In certain implementations, the multifunction coolant manifold
structure is a single, integrated and rigid structure, where the
auxiliary coolant reservoir is integrated with the coolant-commoning
manifold. In this configuration, the coolant-commoning manifold may have
a larger dimension in a first direction, such as the vertical direction,
compared with that of the auxiliary coolant reservoir, which may have a
larger dimension in a second direction, such as the horizontal direction.
Thus, in one embodiment, the coolant-commoning manifold may be an
elongate, vertical manifold, and the auxiliary coolant reservoir may have
a larger cross-sectional area in a horizontal direction to accommodate
additional coolant.

[0038] In certain implementations, the auxiliary coolant reservoir is
coupled in fluid communication with the coolant-commoning manifold via a
detachable coolant conduit or hose. In this configuration, the
coolant-commoning manifold may be the same size as, or have a larger
volume than, the auxiliary coolant reservoir. Alternatively, in one or
more implementations, the auxiliary coolant reservoir may have a larger
volume of coolant than the coolant-commoning manifold. Also note that, in
one or more embodiments, the coolant-commoning manifold may have a
coolant volume twice or larger the size of the coolant volume of the
coolant supply manifold of the cooling system.

[0039] In certain embodiments, the multifunction coolant manifold
structure includes a detachable, field-replaceable unit, which comprises
the auxiliary coolant reservoir. Further, the field-replaceable unit may
include one or more components for at least one of monitoring or
controlling one or more characteristics of coolant within the
multifunction coolant manifold structure. By way of example, the one or
more components may include one or more coolant level sensors (for
sensing a level of coolant within the manifold structure); one or more
vacuum breakers (to prevent cavitation within the pumping assembly of the
cooling system); and/or one or more pressure-relief valves (to ensure
that the cooling system does not over-pressurize), etc. Advantageously,
by associating these components with the field-replaceable unit, the one
or more components may be readily removed for servicing or replacement by
simply exchanging out the field-replaceable unit of the multifunction
coolant manifold structure. Further, by sizing the coolant-commoning
manifold as discussed herein, and by locating the field-replaceable unit
above the coolant-commoning manifold, the field-replaceable unit may be
replaced while the cooling system is operational, that is, while coolant
continues to be pumped through the cooling system to cool the electronic
systems. This can be accomplished, in part, by utilizing quick disconnect
couplings in association with the detachable coolant conduit coupling the
auxiliary coolant reservoir to the coolant-commoning manifold.

[0040] In one or more embodiments, a pumping assembly is provided to
circulate coolant through the cooling system, where the pumping assembly
is coupled in fluid communication to the multifunction coolant manifold
structure via one or more coolant distribution connections. In this
implementation, the multifunction coolant manifold structure includes
both the coolant-commoning manifold and a coolant distribution manifold
portion in a single, rigid manifold structure. In certain embodiments,
the pumping assembly includes multiple coolant pumps (such as two or more
modular pumping units (MPUs)), coupled in parallel fluid communication to
the multifunction coolant manifold structure for selectively pumping
coolant in parallel from the multifunction coolant manifold structure.
The multiple coolant pumps facilitate continued operation of the cooling
system. In operation, only one pumping unit may (depending on the mode)
be active at a time, with modular pumping unit (MPU) redundancy allowing
for, for example, servicing or replacement of an inactive modular pumping
unit from the cooling system, without requiring shut-off of the
electronic systems or electronics rack being cooled. By way of specific
example, quick connect couplings may be employed, along with
appropriately sized and configured hoses to couple, for example, the
multifunction coolant manifold structure, pumping assembly, heat removal
section, and coolant supply manifold, as well as the multiple cooling
structures associated with the electronic systems to be cooled.

[0041] In certain embodiments, the auxiliary coolant reservoir
incorporates a coolant expansion region in an upper portion thereof, and
a coolant fill port disposed below a top of the auxiliary coolant
reservoir, which assists in defining an air pocket in the upper portion
of the reservoir as the coolant expansion region. In one or more
implementations, the auxiliary coolant reservoir further includes one or
more vacuum breakers to prevent cavitation within the cooling system,
and/or one or more pressure-relief valves to prevent the cooling system
from over-pressurizing. Further, in certain implementations, the
auxiliary coolant reservoir may have one or more coolant level sensors
associated therewith to sense a level of coolant within the reservoir, or
more generally, within the multifunction coolant manifold structure.

[0042] FIG. 4 is a schematic depiction of one embodiment of a cooled
electronic assembly configured as a cooled electronics rack 110'',
similar to the above-described cooled electronics rack 110' of FIGS. 3A &
3B. One significant difference in the assembly configuration of FIG. 4,
however, is the provision of a multifunction coolant manifold structure
400, which integrates many of the functions and components described
above in connection with the cooling system provided for the cooled
electronic assembly of FIGS. 3A & 3B. In particular, as illustrated in
FIG. 4, the multifunction coolant manifold structure 400 is shown to
include, in one embodiment, a coolant-commoning manifold 320', a
de-aerator facility 321', a coolant expansion region 322', a coolant
reservoir 323', one or more coolant level sensors 324', one or more
vacuum breakers 325', one or more pressure-relieve valves 326', a
distribution manifold 330' for the pump assembly, as well as one or more
fill or drain ports 328', 329'. As described further below in connection
with the embodiments of FIGS. 5A-6B, these components are differently
configured, however, and/or alternately implemented in comparison to the
discrete components employed in the cooling system described above in
connection with FIGS. 3A & 3B.

[0043] By way of example, FIGS. 5A & 5B depict one detailed embodiment of
a partial cooled electronic assembly, in accordance with one or more
aspects of the present invention. In the depicted embodiment, the cooled
electronic assembly includes a cooling system housing 500, which may be
configured for disposition within, for instance, a lower portion of an
electronics rack, such as within one or more of the above-described
electronics racks. As illustrated, the cooled electronic assembly also
includes multiple electronic systems 301 to be cooled. In the
configuration of FIG. 5A, the electronic systems are shown (by way of
example only) one above the other, above cooling system housing 500, as
they might be positioned within an electronics rack. Note, however, that
this particular configuration is presented as one example only.
Electronic systems 301 each have associated therewith a cooling structure
(not shown), such as a coolant-cooled heat sink, cold plate,
immersion-cooling housing, etc., which facilitates extraction of heat
from the respective electronic system, or from one or more electronic
components within the respective electronic system.

[0044] As illustrated in FIG. 5A, the cooling system includes, in the
depicted embodiment, a coolant supply manifold 310, which includes
respective quick connect couplings 501 that facilitate connection of
appropriately sized and configured hoses 503 to the coolant supply
manifold 310, so as to couple in fluid communication the coolant supply
manifold and the cooling structures associated with the electronic
systems 301. Similar hoses 505 and quick connect couplings 502 are
associated with the multifunction coolant manifold structure 400 of the
cooling system for coupling the cooling structures associated with the
electronics systems 301 in parallel fluid communication with manifold
structure 400 as well.

[0045] As illustrated in FIG. 5A, the multifunction coolant manifold
structure includes a coolant-commoning manifold 320' from which quick
connect couplings 502 extend. In one embodiment, coolant-commoning
manifold 320' is sized larger than coolant supply manifold 310 (e.g.,
2.times. larger or greater in coolant volume) to, in part, slow a flow
rate of coolant exhausting from the cooling structures associated with
the electronic systems 301 as the coolant enters the coolant-commoning
manifold 320'. This slowing of the coolant flow rate is designed so that
entrained air or gas within the coolant is allowed to escape within the
coolant-commoning manifold 320' and rise, in one embodiment, to an
auxiliary coolant reservoir 323' located above the coolant-commoning
manifold 320', and in fluid communication therewith.

[0046] In the example of FIGS. 5A & 5B, the multifunction coolant manifold
structure 400 is a single, integrated and rigid structure, with the
coolant-commoning manifold 320' and auxiliary coolant reservoir 323' in
fluid communication within the integrated structure. As escaping air or
gas rises to the auxiliary coolant reservoir 323' from the
coolant-commoning manifold 320', it is replaced within the
coolant-commoning manifold 320' by coolant from the auxiliary coolant
reservoir 323'. That is, as air or gas rises, coolant drops from the
auxiliary coolant reservoir 323' into the coolant-commoning manifold
320'. In this manner, the multifunction coolant manifold structure 400
inherently functions as a de-aerator. Further, a coolant expansion region
is defined in an upper portion of auxiliary coolant reservoir 323' by
providing, for instance, a coolant fill port 328' in association with the
auxiliary coolant reservoir on a side of the reservoir, spaced below an
upper-most (or top) of the auxiliary coolant reservoir 323'. In this
manner, a volume of air (that is, an air pocket) is formed above the
coolant fill port 328' within the auxiliary coolant reservoir. This
volume of air advantageously allows for safe expansion and contraction of
the coolant within the cooling system due, for instance, to changing
temperatures or pressures.

[0047] As illustrated in FIGS. 5A & 5B, the multifunction coolant manifold
structure 400, and in particular, the auxiliary coolant reservoir 323'
portion thereof, includes connections for one or more components to at
least one of monitor or control one or more characteristics of the
coolant within the multifunction coolant manifold structure. These one or
more components may include, for instance, one or more coolant level
sensors 324' for sensing level of coolant within the multifunction
coolant manifold structure 400, and reporting the level to a cooling
system controller (not shown) for use in possible control action. For
instance, should the level of coolant within the multifunction coolant
manifold structure drop to an unacceptably low level, the level sensor(s)
324' signals could be employed by the controller to signal a service
operator to add coolant to the system. Alternatively, depending on the
sensed level, the controller could automatically shut the cooling system
down, and depending on the implementation, possibly shut the electronic
systems down as well. This might depend, for instance, on whether backup
cooling, such as backup airflow cooling, is integrated within the cooled
electronic assembly. Additionally, the component connections may allow
for connections of one or more vacuum breakers 325', and/or one or more
pressure-relief valves 326', as described above.

[0048] As shown in the figures, the multifunction coolant manifold
structure 400 further includes a coolant distribution manifold portion
with coolant distribution connections 507 (FIG. 5B), which allow coolant
hoses 510 (FIG. 5A) to couple to the manifold structure to receive
coolant from the multifunction coolant manifold structure for
distribution to multiple pumping units, such as the above-described
modular pumping units. In the embodiment of FIG. 5A, three modular
pumping units 335' are illustrated by way of example only, each receiving
(via the respective hose connections 507) coolant from the multifunction
coolant manifold structure. In one implementation, the parallel-coupled
pumping units 335' operate to independently pump coolant through a return
manifold to a heat removal section (as described above), which may also
be disposed within the cooling system housing 500, for instance, behind
the depicted pumping units 335'. In one implementation, the heat removal
section may comprise one or more coolant-to-air heat exchangers, with air
being drawn through the cooling system housing 500 via one or more fan
mechanisms, which in one embodiment, may also be disposed within the
housing, for instance, behind the one or more coolant-to-air heat
exchangers. In an alternate embodiment, the heat removal section could
include one or more liquid-to-liquid heat exchangers to reject heat from
the coolant circulating through the cooling system to, for instance,
facility-chilled liquid, such as building-chilled water. The heat removal
section is coupled to coolant supply manifold 310 via a hose 520 and
appropriate connections.

[0049] As illustrated in FIG. 5A, the cooling system may include, in one
embodiment, a coolant drain hose 521 coupled in fluid communication with
the heat removal section and disposed at a lower-most portion of the
cooling system to facilitate selective draining of coolant from the
cooling system, or filling of coolant into the cooling system, depending
on the current life stage of the system. An appropriate quick connect
coupling may be provided at the end of drain hose 521 to facilitate the
operation.

[0050] Note that FIGS. 5A & 5B depict one embodiment only of an
multifunction coolant manifold structure 400, configured as an integrated
structure, wherein the above-described components or facilities are
advantageously integrated into a common, multipurpose structure. By way
of example, the multifunction coolant manifold structure may be
fabricated of a single, punched, stainless steel sheet metal stamping,
which is bent into the appropriate shape and robotically welded to arrive
at the desired structure. The illustrated manifold structure 400 is used
to common the exhaust flow from the parallel-coupled cooling structures
associated with the electronic systems. In one implementation, these
could be parallel computer nodes or server nodes of an electronics rack,
with four electronic systems being illustrated in FIGS. 5A & 5B, by way
of example only.

[0051] As noted, the upper portion of the multifunction coolant manifold
structure is advantageously configured as an auxiliary coolant reservoir.
In one or more implementations, the cross-sectional area of the auxiliary
coolant reservoir 323' is larger than the cross-sectional area of the
coolant-commoning manifold 320'. In particular, in the depicted
implementation, the coolant-commoning manifold 320' has a larger
dimension in a first, vertical direction compared with that of the
auxiliary coolant reservoir 323', but that the auxiliary coolant
reservoir 323' has a larger horizontal dimension in a second direction
compared with that of the coolant-commoning manifold 320'. Note that the
specific configuration of auxiliary coolant reservoir 323' is presented
by way of example only. The size and configuration of the multifunction
coolant manifold structure may depend, in part, on the available size
within the associated electronics assembly or electronics rack to which
the cooling system provides cooling.

[0052] Note that, in one embodiment, the coolant-commoning manifold 320'
cross-section is made larger than normally required to carry the coolant
flow (for instance, 2.times. or larger) in order to allow the returning,
exhausting coolant to slow down, allowing air and other gas in the
coolant to de-aerate, or come out of solution, within the
coolant-commoning manifold, with any gas bubbles rising to the auxiliary
coolant reservoir portion at the top of the manifold structure, while
coolant from the reservoir replaces the gas bubbles from the
coolant-commoning manifold. Note that the multifunction coolant manifold
structure further may incorporate, for example, in association with the
auxiliary coolant reservoir, one or more level sensors, to allow the
cooling system controller to know the current coolant level state, and
take or signal for action, if required.

[0053] Additionally, features or connections may be provided in the
multifunction coolant manifold structure, such as, in association with
the auxiliary coolant reservoir (in one embodiment), to facilitate
installing vacuum breakers 325' and/or pressure-relief devices 326'. The
vacuum breaker(s) ensures that the auxiliary coolant reservoir is near
atomospheric or slightly negative pressure. This feature may be employed
to prevent the pumps from cavitating due to a negative pressure in the
system. The pressure-relief valves may be provided as a safety feature.
These devices and valves are placed, in one embodiment, in the auxiliary
coolant reservoir, at the highest coolant location within the cooling
system. This ensures that, even if the devices fail in an open state, no
coolant will escape since the coolant is under little or no pressure
within the multifunction coolant manifold structure. During normal
operation, the devices can fail in place, and not cause any functional
problems with the cooling system disclosed herein. The component(s) can
also be safely removed while the cooling system is operational. Note that
in the embodiment of FIGS. 5A & 5B, the vacuum breaker devices 325' and
pressure-relief valves 326' are located in the upper-most portion of the
auxiliary coolant reservoir 323'.

[0054] Mounting brackets may be provided to facilitate convenient mounting
of the coolant supply manifold and multifunction coolant manifold
structure into the electronics rack or frame. Filling and draining of the
cooling system is facilitated by providing one or more fill or drain
ports in association with the multifunction coolant manifold structure.
In the embodiment of FIG. 5A, a fill or drain port 328' is provided in
association with the auxiliary coolant reservoir 323'. This, along with
the discharge hose 521 (FIG. 5A) may be used to fill the cooling system.
For instance, the quick connect coupling at the end of drain hose 521 may
be engaged to pump coolant into the cooling system, and the port 328'
associated with the reservoir may be used to vent air during the filling
operation. During draining, the procedure may be reversed, with air being
allowed in through port 328' as coolant drains from drain hose 521. In
one implementation, the multifunction coolant manifold structure is
filled with coolant, as is the rest of the cooling system, prior to
starting the pumping assembly. The reservoir 323' is, in one
implementation, sized with a sufficient volume of coolant to ensure that
if an unfilled cooling structure associated with one of the electronics
systems is connected to the cooling system during operation, that there
will be sufficient coolant within the cooling system to continue
operation. Note that in the embodiment presented, a large volume of
coolant exists above the multiple parallel-coupled pumps, ensuring a good
source of coolant to prime the pumping units.

[0055] By way of further example, FIGS. 6A & 6B depict an alternate
embodiment of a partial cooled electronic assembly, in accordance with
one or more aspects of the present invention. In this embodiment, the
cooled electronic assembly includes cooling system housing 500 configured
and disposed as described above in connection with FIGS. 5A & 5B.

[0056] Electronic systems 301 each have associated therewith a cooling
structure, such as a coolant-cooled heat sink, cold plate,
immersion-cooling housing, etc., which facilitates extraction of heat
from the respective electronic system, or from one or more electronic
components within the electronic system, to coolant flowing through the
cooling structure. The cooling structures associated with electronic
systems 301 are coupled in parallel between coolant supply manifold 310
and multifunction coolant manifold structure 400'. In particular,
respective quick connect couplings 501 facilitate connection of
appropriately sized and configured hoses 503 to coolant supply manifold
310, so as to couple in fluid communication the coolant supply manifold
and the cooling structures associated with the electronic systems.
Similar hoses 505 and quick connect couplings 502 are associated with
multifunction coolant manifold structure 400' of the cooling system for
coupling the cooling structures associated with the electronic systems
301 in parallel fluid communication with coolant-commoning manifold 320',
as illustrated.

[0057] As in the embodiment of FIGS. 5A & 5B, coolant-commoning manifold
320' is sized larger (for example, 2.times. or greater coolant volume)
than coolant supply manifold 310 to, in part, slow a flow rate of coolant
exhausting from the cooling structures associated with electronic systems
301 as the coolant enters the coolant-commoning manifold 320'. This
slowing of the coolant flow rate is configured or designed so that
entrained air or gas within the coolant is allowed to escape the coolant
within the coolant-commoning manifold 320', and rise, in one embodiment,
to a detachable, field-replaceable unit 600 comprising auxiliary coolant
reservoir 323'. In the embodiment illustrated, field-replaceable unit 600
is located above the coolant-commoning manifold 320', and in fluid
communication therewith via, for instance, one or more hose connections
601 and an appropriately sized and configured detachable coolant conduit
602 coupling, for instance, an upper portion of coolant-commoning
manifold 320' to a lower portion of auxiliary coolant reservoir 323', as
illustrated in FIGS. 6A & 6B.

[0058] In the example of FIGS. 6A & 6B, the multifunction coolant manifold
structure 400' comprises, in part, coolant-commoning manifold 320' and
the separate field-replaceable unit 600, which includes the auxiliary
coolant reservoir 323'. The two structures are in fluid communication via
detachable coolant conduit 602. Thus, as escaping air or gas rises to the
auxiliary coolant reservoir 323' from the coolant-commoning manifold
320', it is replaced within the coolant-commoning manifold 320' by
coolant from the auxiliary coolant reservoir 323'. That is, as air or gas
rises, coolant drops from the auxiliary coolant reservoir 323' in the
field-replaceable unit 600 into the coolant-commoning manifold 320'.
Thus, the multifunction coolant manifold structure 400' is sized and
configured to inherently function as a de-aerator. Further, a coolant
expansion region is defined in an upper portion of auxiliary coolant
reservoir 323' by providing, for instance, coolant fill port 328' in
association with the auxiliary coolant reservoir 323' on a side of the
reservoir, spaced below an upper-most (or top) of the auxiliary coolant
reservoir 323'. In this manner, a volume of air (that is, an air pocket)
is formed above the coolant fill port 328' within the auxiliary coolant
reservoir. This volume of air allows for safe expansion and contraction
of the coolant within the multifunction coolant manifold structure, and
more generally, within the cooling system, due, for instance, to changing
temperatures or pressures.

[0059] As illustrated in FIGS. 6A & 6B, multifunction coolant manifold
structure 400', and in particular, field-replaceable unit 600 thereof,
includes connections for one or more components to monitor or control one
or more characteristics of the coolant within the multifunction coolant
manifold structure. These one or more components may include, for
instance, one or more coolant level sensors 324' for sensing level of
coolant within the multifunction coolant manifold structure 400', and
reporting the level to a cooling system controller (not shown) for use in
possible control action, as described above in connection with FIGS. 5A &
5B. Additionally, the component connections may allow for connections of
one or more vacuum breakers 325', and/or one or more pressure-relief
valves 326', as described above. In an alternate, or further
implementation, a pressure-relief valve 611 may be provided on the end of
a conduit 610, which extends from coolant-commoning manifold 320' along
the side of field-replaceable unit 600, but not in fluid communication
therewith. If an excessive pressure event occurs, coolant may pass up
conduit 610, and through pressure-relief valve 611, into a second conduit
612, which connects from the pressure-relief valve and directs the
exhausting coolant to the bottom of the cooled electronic assembly, such
as to the bottom of the electronics rack. Thus, any coolant released
during the pressure event will safely discharge through the conduits 610
& 612, in one implementation.

[0060] Advantageously, by associating one or more monitoring or control
components 324', 325', 326' with the field-replaceable unit, the
components may be readily removed from the multifunction coolant manifold
structure by simply replacing the field-replaceable unit 600 coupled via
respective quick connect couplings and conduit 602 to coolant-commoning
manifold 320'. Further, by coupling the field-replaceable unit above the
coolant-commoning manifold, the field-replaceable unit may be replaced
while the cooling system is operational, with coolant exhausting from the
multiple cooling structures to the coolant-commoning manifold 320' of the
multifunction coolant manifold structure 400'.

[0061] As in the embodiment of FIGS. 5A & 5B, the multifunction coolant
manifold structure 400' further includes a coolant distribution manifold
portion with coolant distribution connections 507 (FIG. 6B), which allow
coolant hoses 510 (FIG. 6A) to couple to the manifold structure to
receive coolant therefrom for distribution to multiple pumping units
335', such as described above. Note that in the embodiment of FIG. 6A,
three modular pumping units 335' are illustrated by way of example only,
with each receiving, via respective hose connection 507, coolant from the
multifunction coolant manifold structure. In one implementation, the
parallel-coupled pumping units 335' operate to independently pump coolant
through a return manifold (not shown) to a heat removal section (as
described above), which may also be disposed within cooling system
housing 500, for instance, behind the depicted pumping units 335'. In one
implementation, the heat removal section includes one or more
coolant-to-air heat exchangers, with air being drawn through the cooling
system housing 500 via one or more fan mechanisms, which in one
embodiment, may also be disposed within the housing, for instance, behind
the one or more coolant-to-air heat exchangers. In an alternate
embodiment, the heat removal section could include one or more
liquid-to-liquid heat exchangers to reject heat from the coolant
circulating through the cooling system to, for instance, facility-chilled
liquid, such as building-chilled water. The heat removal section may be
coupled to coolant supply manifold 310 via hose 520 and appropriate
connections.

[0062] As with the embodiment of FIGS. 5A & 5B, the cooling system of
FIGS. 6A & 6B may include coolant drain hose 521 coupled in fluid
communication with the heat removal section and disposed at a lower-most
portion of the cooling system to facilitate selective draining of coolant
from the cooling system, or filling of coolant into the cooling system,
depending on the current life stage of the system. Appropriate quick
connect couplings may be provided in association with drain hose 521 to
facilitate the operation.

[0063] By way of example, the coolant-commoning manifold structure 320'
and the field-replaceable unit 600 may each be fabricated of a single,
punched, stainless steel sheet metal stamping, which is bent into the
appropriate shape and robotically welded to arrive at the desired
structure. The illustrated manifold structure 400', and in particular,
the coolant-commoning manifold 320', is used to common the exhaust flow
from the parallel-coupled cooling structures associated with the
electronic systems. In one implementation, these could be parallel
computer nodes or server nodes of an electronics rack, with four
electronic systems of FIGS. 6A being illustrated, by way of example only.

[0064] In certain applications, the height of the coolant electronic
assembly, or more particularly, the height of the electronics rack, may
be too tall for a particular customer facility, and in particular, too
tall for a particular customer door opening. Thus, a height reduction to
the electronics rack may be required, and in such a case, the
multifunction coolant manifold structure of FIGS. 6A & 6B may be
advantageously employed, where a detachable conduit and quick connect
couplings provide the fluid connection between the coolant-commoning
manifold and the auxiliary coolant reservoir of the multifunction coolant
manifold structure.

[0065] In one or more implementations, the cross-sectional area of the
auxiliary coolant reservoir 323' is significantly larger than the
cross-sectional area of the coolant-commoning manifold 320'; that is,
taken transversely through the respective structures. In the depicted
implementation, coolant-commoning manifold 320' has a larger vertical
dimension compared with that of the auxiliary coolant reservoir 323', but
the auxiliary coolant reservoir 323' has, by way of example, a larger
horizontal dimension in a second direction compared with that of the
coolant-commoning manifold 320'. Note that the specific configuration of
the auxiliary coolant reservoir 323' of FIGS. 6A & 6B is presented by way
of example only. The size and configuration of the field-replaceable unit
of the multifunction coolant manifold structure may depend, in part, on
the available size within the associated electronics assembly or
electronics rack to which the cooling system provides cooling.

[0066] Note that the coolant-commoning manifold 320' cross-section is made
larger than normally required in order to allow the returning coolant to
slow down, allowing air and other gas in the coolant to de-aerate, or
come out of solution, within the coolant-commoning manifold, with the gas
bubbles rising to the auxiliary coolant reservoir portion of the
multifunction coolant manifold structure via the conduit 602, while
coolant from the reservoir replaces the gas bubbles within the
coolant-commoning manifold. Advantageously, removal of air or other gas
enhances effectiveness of the coolant since cooling of the electronic
systems is related to the mass flow rate of the coolant.

[0067] As noted, the multifunction coolant manifold structure may further
incorporate, for example, in association with the field-replaceable unit,
one or more level sensors 324' to allow the cooling system controller to
know the current coolant level state, and take or signal for action, if
required. Additional features or connections may be provided in the
field-replaceable unit to facilitate installing vacuum breakers 325'
and/or pressure-relief devices 326'. Alternatively, a pressure-relief
valve 611 may be provided as described above in connection with FIGS. 6A
& 6B. These devices and valves are placed, in one embodiment, at the
highest coolant location within the cooling system. This ensures that,
even if the device or valve should fail in an open state, no coolant will
escape since the coolant is under little or no pressure within the
multifunction coolant manifold structure. During normal operation, the
device or valve can fail in place, and not cause any functional problems
within the cooling system. The component(s) can also be safely removed in
association with the field-replaceable unit, while the cooling system is
operational.

[0068] Mounting bracket 620 may be provided in association with
multifunction coolant manifold structure 400' for convenient mounting of
the multifunction coolant manifold structure within a frame or rack.
Filling and draining of the cooling system is facilitated by providing
one or more fill or drain ports 328' in association with the
multifunction coolant manifold structure. In the embodiment of FIGS. 6A &
6B, a fill or drain port 328' is provided in association with the
field-replaceable unit 600. This, along with discharge hose 521, may be
used to fill the cooling system or drain the cooling system, in a manner
as described above in connection with the embodiment of FIGS. 5A & 5B.

[0069] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of the
invention. As used herein, the singular forms "a", "an" and "the" are
intended to include the plural forms as well, unless the context clearly
indicates otherwise. It will be further understood that the terms
"comprise" (and any form of comprise, such as "comprises" and
"comprising"), "have" (and any form of have, such as "has" and "having"),
"include" (and any form of include, such as "includes" and "including"),
and "contain" (and any form contain, such as "contains" and "containing")
are open-ended linking verbs. As a result, a method or device that
"comprises", "has", "includes" or "contains" one or more steps or
elements possesses those one or more steps or elements, but is not
limited to possessing only those one or more steps or elements. Likewise,
a step of a method or an element of a device that "comprises", "has",
"includes" or "contains" one or more features possesses those one or more
features, but is not limited to possessing only those one or more
features. Furthermore, a device or structure that is configured in a
certain way is configured in at least that way, but may also be
configured in ways that are not listed.

[0070] The corresponding structures, materials, acts, and equivalents of
all means or step plus function elements in the claims below, if any, are
intended to include any structure, material, or act for performing the
function in combination with other claimed elements as specifically
claimed. The description of the present invention has been presented for
purposes of illustration and description, but is not intended to be
exhaustive or limited to the invention in the form disclosed. Many
modifications and variations will be apparent to those of ordinary skill
in the art without departing from the scope and spirit of the invention.
The embodiment was chosen and described in order to best explain the
principles of one or more aspects of the invention and the practical
application, and to enable others of ordinary skill in the art to
understand one or more aspects of the invention for various embodiments
with various modifications as are suited to the particular use
contemplated.